About a polymer having, in the molecule thereof, a carbon-carbon unsaturated bond, its molecular chain can be extended or a crosslinkage network can be formed therein, using an ene/thiol addition reaction with a thiol compound or a hydrosilylation reaction with a hydrosilane compound. Making use of this property, the polymer is used as a raw material of adhesive compositions or curable compositions (Patent Documents 1 and 2). When the polymer is used as the raw material of these curable compositions, an unsaturated bond is generally introduced into a terminal of the molecular chain.
Such a reactive-silicon-group-containing polymer, which is obtained by causing a hydrolyzable-group-containing hydrosilane to hydrosilylate with a carbon-carbon unsaturated bond, is also known as a moisture-reactive polymer. The polymer is included in many industrial products, such as adhesives, sealing agents, coating agents, paints, and tackifiers, and is used in various fields (Patent Document 3).
As a polymer component of such a reactive-group-containing polymer, various polymers are known, examples of which include polymers each having, as a main skeleton thereof, a polyoxyalkylene, saturated hydrocarbon based polymer, or (meth)acrylate copolymer. Out of such polymers, a polyoxyalkylene polymer has a wide applicable scope since the polymer has, for example, the following characteristics: the polymer is relatively low in viscosity at room temperature to be easily handled; and a cured product obtained after reaction of this polymer also shows a good elasticity.
Physical properties of cured products and others that are obtained using a polymer having reactive groups are affected by the structure of the polymer, and the respective positions and the number of the reactive groups. In particular, about the elasticity and the strength of the cured products, factors such as the crosslinkage density or the between-crosslinking-point molecular weight largely affect such physical properties. The polymer needs to have an appropriate between-crosslinking-point molecular weight to gain elasticity. As the polymer is higher in crosslinkage density, the resultant cured product tends to be stronger. In order to gain a cured product having an excellent strength, it is effective to make molecules of the polymer uniform into some degree in between-crosslinking-point molecular weight. In other words, it is preferred that respective chains of the molecules have, at their terminals, reactive groups. Additionally, in order to make the molecules high in crosslinkage density, the reactive groups need to be efficiently present at the terminals.
Any polyoxyalkylene polymer is generally obtained through a polymerization in which an epoxy compound is subjected to ring-opening polymerization. The polymer is obtained by, for example, a polymerization using an alkali catalyst such as KOH, a polymerization using a transition-metal-compound/porphyrin complex catalyst, which is obtained by causing an organic aluminum compound to react with porphyrin (Patent Document 4), a polymerization using a composite metal-cyanide-complex catalyst (Patent Documents 5 to 12), a polymerization using a catalyst made of a polyphosphazene salt (Patent Document 13), or a polymerization using a catalyst made of a phosphazene compound (Patent Document 14).
A polyoxyalkylene polymer having, at its terminal, a hydroxyl group is obtained by a method as described above. By modifying the terminal group of this hydroxyl-group-terminated polyoxyalkylene, a polyoxyalkylene polymer having carbon-carbon unsaturated bonds can be obtained. As an example of the modification, the following is disclosed: a method of using an alkali metal salt to substitute the hydroxyl group with an alkoxy group, and then causing the resultant compound to react with an unsaturated-group-containing halide such as allyl chloride (Patent Document 15); or a method of causing the hydroxyl terminal of the polymer to react with an isocyanate compound having a carbon-carbon unsaturated bond (Patent Document 16).
Disclosed are also methods of using a composite cyanide complex as a catalyst to polymerize an epoxide monomer containing no carbon-carbon unsaturated bond, and subsequently copolymerizing the epoxide monomer containing no carbon-carbon unsaturated bond with an epoxide monomer containing a carbon-carbon unsaturated bond (Patent Documents 17 and 18).